Pump roller assembly with independently sprung rollers

ABSTRACT

A roller assembly comprises a central section with a hub; a plurality of arms coupled to the central section such that each arm is capable of moving independently with respect to the central section; a plurality of spring pins, one spring pin associated with each arm; a plurality of retaining pins, one retaining pin associated with each arm; and a plurality of rollers, one roller coupled to each arm.

BACKGROUND OF THE INVENTION

The present invention generally pertains to pumps. More particularly,but not by way of limitation, the present invention pertains toperistaltic pumps.

Peristaltic pumps may be used in many different applications includingdelivery of fluid during surgical applications (e.g., ophthalmicsurgical applications). Peristaltic pumps may operate by compressing alength of tubing to move a fluid in the tubing or squeeze a molded flowchannel between an elastomeric sheet and a rigid substrate to move afluid between the elastomeric sheet and the rigid substrate. Rotatingroller heads applied against the tubing or elastomeric sheet may be usedfor compressing the tubing or elastomeric sheet. While peristaltic pumpsmay provide predictable flow properties, they may also impart unwantedflow and pressure pulsations. In addition, the rotating roller heads mayfail to properly compress the tubing or elastomeric sheet. It would bedesirable to have a peristaltic pump roller assembly that overcomesthese problems.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, a roller assembly comprisesa central section with a hub; a plurality of arms coupled to the centralsection, each arm having a radial section, an arcuate section, and abent section; and a plurality of rollers, one roller coupled to the bentsection of each arm. The arms may be flexible such that the rollers arecapable of moving with respect to the central section when the armsflex. The roller may be coupled to the bent section with a pin. The armsand the rollers are distributed around the hub. A rolling surface of therollers is generally parallel with a flat surface of the centralsection. The rolling surface of the rollers is arranged to engage apolymer sheet or flexible tubing throughout travel of the arms. Thecentral section and arms may be cut from a single sheet of material. Inaddition, the central section may comprise a first flat surface, theradial section of the arm may comprise a second flat surface, and theaxial section of the arm may comprise a fourth flat surface in which thefirst flat surface generally parallel to the second and third flatsurfaces. Further, the bent section may comprise a fourth flat surface,the fourth flat surface arranged at an angle of between 900 and 140degrees with respect to the first, second and third flat surfaces. Theroller may be coupled to the bent section via a pin and cap pin

In another embodiment of the present invention, a roller assembly foruse with a peristaltic pump system comprises a central section with ahub; a plurality of arms coupled to the central section, each arm havinga radial section, an arcuate section, and a bent section; a plurality ofrollers, one roller coupled to the bent section of each arm; wherein thecentral section comprises a first flat surface, the radial section ofthe arm comprises a second flat surface, and the axial section of thearm comprises a fourth flat surface, the first flat surface generallyparallel to the second and third flat surfaces, and further wherein thebent section comprises a fourth flat surface, the fourth flat surfacearranged at an angle with respect to the first, second and third flatsurfaces.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of flexible armscoupled to the central section; a plurality of spring pins, one springpin coupled to each of the plurality of flexible arms; a plurality ofarms coupled to the central section such that each arm is capable ofpivoting independently with respect to the central section; and aplurality of rollers, one roller coupled to each of the plurality ofarms. The roller may be coupled to the arm with a pin. The arms and therollers may be distributed around the hub. A rolling surface of therollers is generally parallel with a flat surface of the centralsection. The arm has a stop located at an end of the arm, the stopengages the central section to limit a range of pivoting motion of thearm. The arm may be coupled to a pivot, the pivot located adjacent tothe stop. Each of the plurality of arms may have a flat that contactsthe plurality of spring pins. The spring pin exerts a force on the flat,the force provided by the flexible arm. The spring pin presses on theflat to bias the arm in an unpivoted position whereby the stop contactsthe central section. The plurality of flexible arms and a top surface ofthe central section may be formed from single sheet of material. Therolling surface of the rollers may be arranged to engage a polymer sheetor flexible tubing throughout a range of travel of the arms.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of flexible armscoupled to the central section; a plurality of spring pins, one springpin coupled to each of the plurality of flexible arms; a plurality ofarms coupled to the central section such that each arm is capable ofpivoting independently with respect to the central section, each armhaving a pivot located adjacent to a stop; and a plurality of rollers,one roller coupled to each of the plurality of arms; wherein each springpin exerts a force on an associated arm, the force provided by anassociated flexible arm so as to bias the arm in a nonpivoted position.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of spring assembliescoupled to the central section; a plurality of arms coupled to thecentral section such that each arm is capable of pivoting independentlywith respect to the central section; and a plurality of rollers, oneroller coupled to each of the plurality of arms. Each roller may becoupled to each arm with a pin. The arms and the rollers may bedistributed around the hub. A rolling surface of the rollers isgenerally parallel with a flat surface of the central section. Each ofthe plurality of arms may have a stop located at an end of each arm,each stop engages the central section to limit a range of pivotingmotion of each arm. Each of the plurality of arms may be coupled to apivot, the pivot located adjacent to the stop. Each spring assemblyfurther comprises a spring pin. Each of the plurality of arms may have aflat that contacts the plurality of spring pins. Each spring pin exertsa force on each flat, the force provided by each spring assembly. Eachspring pin presses on each flat to bias each arm in an unpivotedposition in which each stop contacts the central section. The rollingsurface of the rollers is arranged to engage a polymer sheet or flexibletubing throughout a range of travel of the arms.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of spring assembliescoupled to the central section; a plurality of spring pins, one springpin coupled to each of the plurality of spring assemblies; a pluralityof arms coupled to the central section such that each arm is capable ofpivoting independently with respect to the central section, each armhaving a pivot located adjacent to a stop; and a plurality of rollers,one roller coupled to each of the plurality of arms; wherein each springpin exerts a force on an associated arm, the force provided by anassociated spring assembly so as to bias the arm in a nonpivotedposition.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of arms coupled tothe central section such that each arm is capable of movingindependently with respect to the central section; a plurality of springpins, one spring pin associated with each arm; a plurality of retainingpins, one retaining pin associated with each arm; and a plurality ofrollers, one roller coupled to each arm. The roller may be coupled tothe arm via an axle and a pin. The arms and the rollers may bedistributed around the hub. A rolling surface of the roller may begenerally parallel to a flat surface of the central section. A pluralityof springs may be located around the plurality of spring pins, eachspring located between each arm and the central section. The spring pinmay be located in a first bore in the central section, the retaining pinmay be located in a second bore in the central section, the spring pinmay be fixed to the arm, and the retaining pin may be fixed to thecentral section. The roller may be constrained by the retaining pin andthe spring pin to move along an axis defined by the retaining pin. Thespring exerts a force on each arm thereby biasing each arm away from thecentral section. One end of the spring may be located in a recess in thecentral section and the other end of the spring may be located in arecess in the arm. The rolling surface of the rollers may be arranged toengage a polymer sheet or flexible tubing throughout a range of travelof the arms.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub; a plurality of arms coupled tothe central section such that each arm is capable of movingindependently with respect to the central section; a plurality of springpins located is a plurality of first bores in the central section, onespring pin fixed to each arm; a plurality of retaining pins located in aplurality of second bores in the central section and fixed to thecentral section, one retaining pin associated with each arm; and aplurality of rollers, one roller coupled to each arm; wherein therollers are constrained by the retaining pins and the spring pins tomove along an axis defined by the retaining pins.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub, the central section having aplurality of pivots located around the central section; a plurality ofarms, each arm having a roller end and a pivot end, the pivot endscoupled to the central section at the plurality of pivots such that eacharm is capable of pivoting independently with respect to the centralsection, the roller ends and pivot ends of each arm located a distanceof at least one roller width away from each other; a plurality ofrollers, one roller coupled to each of the roller ends of the pluralityof arms; wherein the plurality of rollers and arms are located aroundthe central section such that the pivot is located a distance away fromthe roller. Each roller may be coupled to each arm via an axle and apin. A rolling surface of the rollers may be generally parallel with aflat surface of the central section. A plurality of springs may belocated adjacent to each roller. The plurality of springs may be locatedin a plurality of spring bores in the central section. Each arm furthercomprises a pair of pivot pins, the pair of pivot pins coupling the armto the central section at the pivot. Each arm further comprises a hubretaining surface and a spring coupling surface located near the rollerarm end of the arm. The spring coupling surface contacts the spring. Thehub retaining surface contacts the hub such that the hub retains the armadjacent to the central section. When an arm pivots, a roller surface ofthe roller coupled to the arm is generally parallel to a surface of thecentral section. The plurality of pivots may be located around aperiphery of the central section. The rollers are located interior theperiphery of the central section. A rolling surface of the rollers isarranged to engage a polymer sheet or flexible tubing throughout a rangeof travel of the arms.

In another embodiment of the present invention, a roller assemblycomprises a central section with a hub, the central section having aplurality of pivots located around the central section; a plurality ofarms, each arm having a roller arm end and a pivot end, the pivot endscoupled to the central section at the plurality of pivots such that eacharm is capable of pivoting independently with respect to the centralsection, the roller arm ends and pivot ends of each arm located adistance of at least one roller width away from each other; a hubretaining surface and a spring coupling surface located near the rollerarm end of the arm; a plurality of rollers, one roller coupled to eachof the roller ends of the plurality of arms; and a plurality of springs,one spring located adjacent to each roller; wherein the plurality ofrollers and arms are located around the central section such that thepivot is located a distance away from the roller, the spring couplingsurface contacts the spring, and the hub retaining surface contacts thehub such that the hub retains the arm adjacent to the central section.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the description, serve to explain theprinciples of the invention.

FIG. 1 a is a front view of an elastomeric sheet with two pump segments,according to an embodiment of the present invention.

FIG. 1 b is a back view of the elastomeric sheet with two pump segments,according to an embodiment of the present invention.

FIG. 1 c is a front view of a substrate for two pump segments, accordingto an embodiment of the present invention.

FIG. 1 d is a back view of the substrate for two pump segments,according to an embodiment of the present invention.

FIG. 2 a is a top view of a roller head, according to an embodiment ofthe present invention.

FIG. 2 b is a bottom view of the roller head, according to an embodimentof the present invention.

FIGS. 3 a and 3 b are isometric views of an expanded cassette assemblyview, according to an embodiment of the present invention.

FIG. 3 c is a side view of the roller head and motor, according to anembodiment of the present invention.

FIG. 3 d is an outline of the roller head engaging the sheet, accordingto an embodiment of the present invention.

FIG. 4 a is an isometric view of a roller assembly according to theprinciples of the present invention.

FIG. 4 b is a side cut away view of the roller assembly of FIG. 4 aaccording to the principles of the present invention.

FIG. 4 c is a top view of the roller assembly of FIG. 4 a according tothe principles of the present invention.

FIG. 5 a is an isometric view of a roller assembly according to theprinciples of the present invention.

FIG. 5 b is a side cut away view of the roller assembly of FIG. 5 aaccording to the principles of the present invention.

FIG. 6 a is an isometric view of a roller assembly according to theprinciples of the present invention.

FIG. 6 b is a side cut away view of the roller assembly of FIG. 6 aaccording to the principles of the present invention.

FIG. 7 a is a side view of an arm of the roller assembly of FIG. 6 aaccording to the principles of the present invention.

FIG. 7 b is an end view of an arm of the roller assembly of FIG. 6 aaccording to the principles of the present invention.

FIG. 8 a is an isometric view of a roller assembly according to theprinciples of the present invention.

FIG. 8 b is a side view of the roller assembly of FIG. 8 a according tothe principles of the present invention.

FIG. 8 c is a side cut away view of the roller assembly of FIG. 8 aaccording to the principles of the present invention.

FIG. 9 is a side cut away view of a single roller head and arm assemblyof the roller assembly of FIG. 8 a according to the principles of thepresent invention.

FIG. 10 is a side view of an arm of the roller assembly of FIG. 8 aaccording to the principles of the present invention.

FIG. 11 a is an isometric view of a roller assembly according to theprinciples of the present invention.

FIG. 11 b is a partial isometric view of the roller assembly of FIG. 11a according to the principles of the present invention.

FIG. 11 c is a partial isometric view of the roller assembly of FIG. 11a according to the principles of the present invention.

FIG. 11 d is an expanded isometric view of the roller assembly of FIG.11 a according to the principles of the present invention.

FIG. 12 a is an isometric view of an arm of the roller assembly of FIG.11 a according to the principles of the present invention.

FIG. 12 b is an isometric view of an arm of the roller assembly of FIG.11 a according to the principles of the present invention.

FIG. 12 c is an isometric view of an arm of the roller assembly of FIG.11 a according to the principles of the present invention.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are intended to provide a further explanation of the presentinvention as claimed.

DETAILED DESCRIPTION

Reference is now made in detail to the exemplary embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are usedthroughout the drawings to refer to the same or like parts.

FIGS. 1 a-b illustrate a sheet 107 (such as an elastomeric sheet) forcoupling to a substrate 105 (e.g., any of substrates 105 a-c—generallyreferred to herein as substrate 105) to define two or more pump segments(e.g., any of pump segments 103 a-b—generally referred to herein as pumpsegments 103) in a cassette 100 (e.g., any of cassettes 100a-b—generally referred to herein as cassette 100). Cassette 100 may usepump segments 103 to provide aspiration and/or infusion of fluid 155(e.g., see FIG. 5 c) for a surgical console (e.g., an ophthalmicsurgical console 701 as seen in FIG. 7). FIGS. 1 c-d illustrate anembodiment of substrate 105 a (other embodiments of the substrate 105are also contemplated). In various embodiments, the two or more pumpsegments 103 may be formed between the sheet 107 and the substrate 105of the cassette 100. Sheet 107 may be made of a flexible, moldablematerial such as silicone rubber or thermoplastic elastomer. Othermaterials are also contemplated. Substrate 105 may be made of a materialthat is rigid with respect to sheet 107, such as a rigid thermoplastic,and may be made by any suitable method, such as machining or injectionmolding. In some embodiments, the sheet 107 may be bonded ormechanically attached to the substrate 105 (e.g., through adhesive, heatfusion, mechanical crimping, rivets, etc). In some embodiments,protrusions 151 a-n on an outer perimeter and/or interior of sheet 107may engage corresponding recesses 153 a-n on substrate 105 to connectthe sheet 107 to the substrate 105 and help prevent rotation of thesheet 107 when acted upon by rollers (e.g., see rollers 201 a-n in FIG.2 b) (rollers 201 a-n—generally referred to herein as rollers 201). Asused herein, the label “a-n” is used to refer to the various elements inthe presented embodiments for that element. For example, “rollers 201a-n” is used to refer to the rollers shown in, for example, FIG. 2 b(FIG. 2 b shows 5 rollers—the two rollers in FIG. 2 b are labeled 201 aand 201 n although some of the rollers in each of these FIGs. may nothave specific labels). In some embodiments, protrusions 117 a,b (whichmay outline the respective pump segments 103) may fit into correspondingrecesses 119 a,b (see FIG. 3 a). Protrusions 117 a,b (and/or 151 a-n)may be secured to respective recesses 119 a,b (and/or 153 a-n) to retainthe sheet 107 to the substrate 105. In some embodiments, protrusions 117a,b (and/or 151 a-n) may be secured to respective recesses 119 a,b(and/or 153 a-n) through a mechanical/friction fit, adhesive, heatfusion, etc. In some embodiments, protrusions 117 a,b may be secured torespective recesses 119 a,b to form a seal to prevent escape of a pumpfluid 155 (such as BSS™ (balanced salt solution)) from the pump segments103.

In various embodiments, fluid 155 may be pumped through the cassette 100when a series of rollers 201 engage the two or more pump segments 103 onthe cassette 100. FIGS. 2 a-b illustrate a roller head 203 with rollers201. FIGS. 3 a-b illustrate isometric views of an embodiment of anexpanded cassette assembly view showing the rollers 201, the sheet 107,and the substrate 105. FIG. 3 c illustrates an embodiment of the rollerhead 203 and corresponding peristaltic pump motor 205. In someembodiments, the rollers 201 on the roller head 203 may be radiallymounted from an axis of rotation 207 of the peristaltic pump motor 205(e.g., a stepper or direct current (DC) servo motor, or other motor(such as an alternating current (AC) motor)) and may be configured tocompress the pump segments 103 against the underlying substrate 105. Therollers 201 may be mounted to pump motor 205 through roller head 203 andshaft 223 such that pump motor 205 may rotate roller head 203 in a planegenerally normal or perpendicular to axis 207 of shaft 223 (see alsosolid circle 207 in FIG. 3 d showing where the axis 207 is perpendicularto the plane of the rollers 201), and the longitudinal axes of rollers201 may be generally radial to the axis of shaft 223. FIG. 3 dillustrates an embodiment of the rollers 201 engaging two pump segments103 a,b on sheet 107 (indicated in dashed lines). The two or more pumpsegments 103 on the cassette 100 may produce additional flow (e.g.,approximately twice the flow for two segments as opposed to one) than ifthe cassette 100 had only one pump segment engaging the roller head 203.

In various embodiments, the two (or more) active pump segments 103 inthe sheet 107 may be acted upon by a single hub roller assembly (e.g.,including rollers 201 and roller head 203). As rollers 201 engage thepump segments 103, each roller may first roll over a transition region(e.g., transition regions 115 a-d—generally referred to herein astransition region 115) with an underlying transition channel (e.g.,transition channels 157 a-d—generally referred to herein as transitionchannel 157). In some embodiments, the sheet 107 may not includetransition regions 115 and the substrate 105 may not include transitionchannels 157. As the rollers 201 roll off of the transition region 115(and correspondingly, off of the transition channel 157), the rollers201 may form an internal seal within the pump segment 103 (e.g., atpoint 161 indicated with dashed lines on pump segment 103 a and at point169 on pump segment 103 b) by pressing the sheet 107 fully againstsubstrate 105 at the seal point (in the absence of transition regionsand transition channels, the roller 201 may form a seal at the start ofthe roller's engagement with the sheet 107).

FIG. 4 a is an isometric view of a roller assembly according to theprinciples of the present invention. In the roller assembly 400 of FIG.4 a, rollers 410 a-n are connected to arms 430 a-n via pins 420 a-n.Rollers 410 a-n are capable of rotating about pins 420 a-n. Arms 430 a-nare coupled to central section 455. Hub 450 is located in centralsection 455 and forms a center of rotation. In addition, hub 450provides an opening for connection of the roller assembly 400 to a motoror other device capable of rotating roller assembly 400 about hub 450.The roller assembly 400 rotates about hub 450.

FIG. 4 b is a side cut away view of the roller assembly of FIG. 4 aaccording to the principles of the present invention. In FIG. 4 b, theinterior of roller 410 is depicted. Roller 410 a-n has hollow bore thatreceives pin 420 a. Pin 420 a is also fixed to arm 430. Roller 410rotates about pin 420 a. A cap pin 440 a retains roller 410 on pin 420a. Arms 430 a-n are bent at an angle of greater than 90 degrees so thatthe bottom surface of roller 410 a-n (the surface of roller 410 a-n thatcontacts the elastomeric sheet or tubing) is generally parallel to theportion of arm 430 a-n that is coupled to hub 450. Roller 410 a-n isgenerally conical (and more particularly, roller 410 a-n is shaped likea portion of a cone). As such, the rolling surfaces of roller 410 a-nare not parallel to (or disposed at an angle with respect to) the pin420 a-n and cap pin 440 a-n.

FIG. 4 c is a top view of the roller assembly of FIG. 4 a according tothe principles of the present invention. In FIG. 4 c, the configurationof arms 430 a-n are more clearly shown. As an example, one arm (430 b)comprises three sections: a radial section 460 b, an arcuate section 470b, and a bent section 480 b. Bent section 480 b includes a hole 490 bfor receiving pin 420 b. Radial section 460 b connects arcuate section470 b with central section 455. The top surfaces of arcuate section 470b, radial section 460 b, and central section 455 are all generallyparallel. Arcuate section 470 b connects radial section 460 b with bentsection 480 b. Bent section 480 b is bent at an angle with respect toarcuate section 470 b. In this example, the angle is greater than 90degrees so that the rolling surface of roller 410 b is generallyparallel with the surface of arcuate section 470 b (as shown in FIG. 4 bfor roller 410 a). A hole 490 b in bent section 480 b receives a pinthat secures roller 410 b.

Central section 455, radial section 460, arcuate section 470 and bentsection 480 may all be stamped or formed from a single sheet ofmaterial. In such a case, arcuate section 470 is capable of flexing upand down with respect to central section 455. Accordingly, arcuatesection 470 has a spring constant associated with it. When the rollerassembly 400 is engaged with a flexible tubing or cassette, the arcuatesection 470 presses the roller 410 firmly against the flexible tubing orcassette. The spring constant associated with arcuate section 470 may bedesigned such that a desired force is applied by roller 410 on theflexible tubing or cassette. For example, when the arcuate section 470is formed from a sheet of steel, a thin sheet may be used to provide asmall spring constant or a thicker sheet may be used to provide agreater spring constant. In addition, the force applied by arcuatesection 470 on roller 410 keeps roller 410 engaged with the flexibletubing or cassette (for example, when the flexible tubing or cassette isuneven due to fluid and material in it).

FIG. 5 a is an isometric view of a roller assembly according to theprinciples of the present invention. FIG. 5 b is a side cut away view ofthe roller assembly of FIG. 5 a according to the principles of thepresent invention. The structure and operation of the roller assembly ofFIGS. 5 a-5 b is similar to that of FIGS. 4 a-c. In the roller assembly500 of FIGS. 5 a-5 b, rollers 510 a-n are rotatably connected to arms525 a-n via pins 520 a-n. Accordingly, rollers 510 a-n are capable ofrotating about pins 520 a-n. Arms 525 a-n are coupled to central section555 via pivot 545 a-n. Hub 550 is located in central section 555 andforms a center of rotation. In addition, hub 550 provides an opening forconnection of the roller assembly 500 to a motor or other device capableof rotating roller assembly 500 about hub 550. The roller assembly 500rotates about hub 550. The structure and configuration of rollers 510a-n is the same as that of rollers 410 a-n.

As more clearly seen in FIG. 5 b, arm 525 n pivots about pivot 545 n.Spring pin 535 n is coupled to flexible arm 530 n. Flexible arm 530 nexerts a force on arm 525 n via spring pin 535 n. Stop 565 n is locatedat one end of arm 525 n and rests against a portion of central section555. The force exerted by flexible arm 530 n holds stop 565 n againstcentral section 555, and thus keeps arm 525 n in a first, unpivotedposition. As roller 510 n is engaged with a polymer sheet or tubing,arms 525 n can pivot upwards by deflecting flexible arm 530 n. In thismanner, as a force is applied to roller 510 n, arm 525 n pivots aboutpivot 545 n. As arm 525 n pivots, it pushes on spring pin 535 n anddeflects flexible arm 530 n. Flexible arm 530 n may be designed toprovide a suitable force against arm 525 n via spring pin 535 n. Assuch, flexible arm 530 n may have a spring constant sufficient to keeproller 510 n pressed securely against a polymer sheet or flexibletubing.

FIG. 6 a is an isometric view of a roller assembly according to theprinciples of the present invention. FIG. 6 b is a side cut away view ofthe roller assembly of FIG. 6 a according to the principles of thepresent invention. The structure and operation of the roller assembly ofFIGS. 6 a-6 b is similar to that of FIGS. 4 a-4 c and 5 a-5 b. In theroller assembly 600 of FIGS. 6 a-6 b, rollers 610 a-n are rotatablyconnected to arms 625 a-n via pins 620 a-n. Accordingly, rollers 610 a-nare capable of rotating about pins 620 a-n. Arms 625 a-n are coupled tocentral section 655 via pivot 645 a-n. Hub 650 is located in centralsection 655 and forms a center of rotation. In addition, hub 650provides an opening for connection of the roller assembly 600 to a motoror other device capable of rotating roller assembly 600 about hub 650.The roller assembly 600 rotates about hub 650. The structure andconfiguration of rollers 610 a-n is the same as that of rollers 410 a-n.

As more clearly seen in FIG. 6 b, arm 625 n pivots about pivot 645 n.Spring assembly 635 n exerts a force on arm 625 n. Stop 665 n is locatedat one end of arm 625 n and rests against a portion of central section655. The force exerted by spring assembly 630 n holds stop 665 n againstcentral section 655, and thus keeps arm 625 n in a first, unpivotedposition. As roller 610 n is engaged with a polymer sheet or tubing,arms 625 n can pivot upwards by deflecting spring assembly 630 n. Inthis manner, as a force is applied to roller 610 n, arm 625 n pivotsabout pivot 645 n. As arm 625 n pivots, it pushes on spring assembly 630n. Spring assembly 630 n may be designed to provide a suitable forceagainst arm 625 n. As such, spring assembly 630 n may have a springconstant sufficient to keep roller 610 n pressed securely against apolymer sheet or flexible tubing.

FIG. 7 a is a side view of an arm of the roller assembly of FIGS. 5 a-5b and 6 a-6 b according to the principles of the present invention. FIG.7 b is an end view of an arm of the roller assembly of FIG. 5 a-5 b and6 a-6 b according to the principles of the present invention. Arm 725has a hole 749 n that accepts a pin to engage a roller. A pivot hole 745accepts a pin that allows arm 725 to pivot about pivot hole 745. A stop765 is located on one end of arm 725. A flat 759 is located on a top endof arm 725. Flat 759 provides a surface for engagement with a spring pin(as in FIGS. 5 a-5 b) or spring assembly (as in FIGS. 6 a-6 b). FIG. 7 bmore clearly shows the hole 749 that accepts a pin to engage a roller.

FIGS. 8 a, 8 b, and 8 c are an isometric view, a side view, and a sidecut away view (respectively) of a roller assembly according to theprinciples of the present invention. Roller assembly 800 has a centralsection 855 with a hub 850, rollers 810 a-n, pins 820 a-n, arms 825 a-n,spring pins 830 a-n, retaining pins 833 a-n, springs 837 a-n, and axles823 a-n. Hub 850 is centrally located in central section 855. Rollerassembly 800 rotates around hub 850. Rollers 810 a-n are coupled to arms825 a-n by pins 820 a-n. Each arm 825 a-n is coupled to a spring pin 830a-n and a retaining pin 833 a-n. One end of spring pin 830 a-n issecured to arm 825 a-n and the other end of spring pin 830 a-nterminates in a cap that rests on top of central section 855. Spring pin830 a-n is located in and can move up and down in a bore in centralsection 855. Similarly, one end of retaining pin 833 a-n is secured toarm 825 a-n and the other end of retaining pin 833-n terminates on topof central section 855. Retaining pin 833 a-n is located in and can moveup and down in a bore in central section 855. Movement of arm 825 a-n isconstrained by retaining pin 833 a-n. Arm 825 a-n can only move up anddown along retaining pin 833 a-n. A spring 837 a-n is located betweenarm 825 a-n and central section 855. One end of spring 837 a-n iscontained in a bore in central section 855, and the other end of spring837 a-n is contained in a bore in arm 825 a-n. In this manner, spring837 a-n exerts a force that separates central section 855 from arm 825a-n.

Roller 810 a-n is arranged such that the surface of roller 810 a-n thatcontacts a polymer sheet or tubing is generally parallel to a surface ofcentral section 855. In this manner, substantially all of the rollersurface of roller 810 a-n makes contact with the polymer sheet or tubingas the roller 810 a-n moves. Because of retaining pin 833 a-n, roller810 a-n moves only up and down with respect to central section 855. Asroller 810 a-n moves up and down, retaining pin 833 a-n slides in a borein central section 855. Spring 837 a-n presses down on arm 825 a-n (andattached roller 810 a-n). As such, spring 837 a-n biases arm 825 a-naway from central section 855. The structure and configuration ofrollers 810 a-n is the same as that of rollers 410 a-n.

FIG. 9 is a side cut away view of a single roller head and arm assemblyof the roller assembly of FIG. 8 a according to the principles of thepresent invention. In FIG. 9, retaining arm 833 a-n is secured to arm825 a-n. An axle 823 a-n is also secured to arm 825 a-n. Roller 810 a-nis secured to axle 823 a-n by pin 820 a-n and rotates about axle 823a-n. The location of spring 837 a-n is also show with respect to arm 825a-n. A recess 843 a-n receives spring pin 830 a-n.

FIG. 10 is a side view of an arm of the roller assembly of FIG. 8 aaccording to the principles of the present invention. In FIG. 10, arm825 a-n has a hole 842 a-n for receiving axle 823 a-n, a hole 844 a-nfor receiving retaining pin 833 a-n, and a recess 843 a-n for receivingspring pin 833 a-n.

FIGS. 11 a-11 d are various isometric views of a roller assemblyaccording to the principles of the present invention. In FIGS. 11 a-11d, roller assembly 900 has a central section 955. A hub 950, rollers 910a-n, pins 920 a-n, arms 925 a-n, pivots 930 a-n, axles 923 a-n, springs937 a-n, pivot pins 942 a-n and 944 a-n, roller arm ends 926 a-n, hubbore 957, and spring bores 956 a-n. In FIG. 11 a, rollers 910 a-n areheld to arms 925 a-n by pins 920 a-n. Arms 825 a-n are coupled tocentral section 955 such that arms 925 a-n can pivot with respect tocentral section 955. A hub 950 is located at the center of centralsection 955. Roller assembly 900 rotates about hub 950. Rollers 910 a-nare oriented such that the rolling surface of rollers 910 a-n contact apolymer sheet or flexible tubing during a peristaltic pumping process.

As more clearly shown in FIG. 11 b, rollers 910 a-n are connected toarms 925 a-n via axles 923 a-n and pins 920 a-n. Springs 937 a-n arelocated in central section 955 beneath rollers 910 a-n (moreparticularly beneath arms 925 a-n that couple to rollers 910 a-n).Pivots 930 a-n provide an attachment location for arms 925 a-n. Arms 925a-n are attached to central section 955 at pivots 930 a-n. Arms 925 a-npivot with respect to central section 955 at pivots 930 a-n. Thestructure and configuration of rollers 910 a-n is the same as that ofrollers 410 a-n.

FIG. 11 c more clearly shows the structure of arms 925 a-n and thelocation of springs 937 a-n. In FIG. 11 c, arms 925 a-n each have twopivot pins 942 a-n and 944 a-n. The pivot pins, 942 a-n and 944 a-n, fitinto pivots 930 a-n of central section 955. In this manner, the pivotpins, 942 a-n and 944 a-n, each fit into the recesses that define thepivots 930 a-n in central section 955. Pivot pins, 942 a-n and 944 a-n,couple arms 910 a-n to central section 955. Springs 937 a-n are locatedbeneath arms 925 a-n and provide a spring force that biases arms 925 a-nupward. Hub 950 engages a hub engaging surface 968 a-n (in FIG. 12 a)that retains arms 925 a-n.

FIG. 11 d shows how the arms 925 a-n, springs 937 a-n, and centralsection 955 fit together. Central section 955 has a hub bore 957 thatreceives hub 950, and spring bores 956 a-n that receive springs 937 a-n.In addition, central section 955 also has a pair of pivots 930 a-n foreach arm 925 a-n. Each arm 925 a-n has a spring 937 associated with it.Springs 937 a-n fit into spring bores 956 a-n. Springs 937 a-n areretained in spring bores 956 a-n by a back surface of central section955 (shown in FIG. 11 c) and hub 950 (which presses arms 925 a-n againstsprings 937 a-n and serves to retain arms 937 a-n). Pivot pins 942 a-nand 944 a-n fit into pivots 930 a-n in central section 955.

FIGS. 12 a-12 c are various isometric views of an arm of the rollerassembly of FIGS. 11 a-11 d according to the principles of the presentinvention. Arms 925 a-n have a pair of pivot pins 942 a-n and 944 a-n, aspring coupling surface 967 a-n, a hub retaining surface 968 a-n, and aroller arm end 926 a-n. Rollers 910 a-n are coupled to arms 925 a-n atthe roller end 926 a-n. Axles 923 a-n are fixed to roller arms end 926a-n. Rollers 910 a-n are held on axles 923 a-n by pins 920 a-n. Each arm925 a-n has a pivot end that couples the arm to the central section 955.Arm 925 a-n has a generally curved or arcuate profile such that theroller end 926 a-n and pivot end (end on which pivots 942 a-n and 944a-n reside) are arranged to couple the arm 925 a-n to the centralsection 955 and to allow for proper alignment of roller 910 a-n.Generally, the pivot end of arm 925 a-n is at least one roller widthdistance from the roller end 926 a-n of arm 925 a-n. In addition, theroller end 926 a-n of the arm 925 a-n is located a distance away in twodifferent directions from the pivot end of the arm 925 a-n. In thismanner, arm 925 a-n is curved with respect to two different planes. Withthe pivot end fixed to a periphery of the central section 955, theroller end 926 a-n of arm 925 a-n is located interior to the peripheryof central section 955 and above central section 955.

Each arm 925 a-n has a spring coupling surface 967 a-n associated withit. The spring coupling surface 967 a-n rests against spring 937 a-n.Spring coupling surface 967 a-n has a lip that receives an end of spring937 a-n. Arms 925 a-n is configured such that a surface of roller 910a-n contacts a polymer sheet or flexible tubing during the entire travelof arm 925 a-n (as arm 925 a-n pivots with respect to central section955). Springs 937 a-n bias arms 925 a-n away from central section 955.As rollers 910 a-n encounter variations in a polymer sheet or flexibletubing, rollers 925 a-n are pressed towards central section 955 thuscompressing spring 937 a-n. In this manner, rollers 910 a-n are heldtightly against a polymer sheet or flexible tubing by springs 937 a-n.Because of the shape of arms 925 a-n and the distance between therollers 910 a-n and the pivots 930 a-n, rollers 910 a-n are held againsta polymer sheet or flexible tubing such that a surface of rollers 910a-n press firmly against the polymer sheet or flexible tubing. Therolling surface of rollers 910 a-n remains general parallel to thepolymer sheet or flexible tubing throughout travel of the arms 925 a-n.

Regardless of the embodiment described above, the rollers are biasedagainst a polymer sheet or flexible tube such that the rolling surfaceof the rollers presses against the polymer sheet or flexible tube. Therolling surface of the rollers (i.e. the surface that contacts thepolymer sheet or flexible tube) is generally parallel to the polymersheet or flexible tube so as to press against it. The rollers aremaintained against the polymer sheet or flexible tube by a spring forceso as to provide peristaltic pumping as the roller assembly rotates.

From the above, it may be appreciated that the present inventionprovides an improved peristaltic pump system. The present inventionprovides independent roller heads for use with a peristaltic pumpsystem. The present invention is illustrated herein by example, andvarious modifications may be made by a person of ordinary skill in theart.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. A roller assembly comprising: a central sectionwith a hub; a plurality of arms coupled to the central section such thateach arm is capable of moving independently with respect to the centralsection; a plurality of spring pins, one spring pin associated with eacharm; a plurality of retaining pins, one retaining pin associated witheach arm; and a plurality of rollers, one roller coupled to each arm. 2.The roller assembly of claim 1 wherein the roller is coupled to the armvia an axle and a pin.
 3. The roller assembly of claim 1 wherein thearms and the rollers are distributed around the hub.
 4. The rollerassembly of claim 1 wherein a rolling surface of the roller is generallyparallel to a flat surface of the central section.
 5. The rollerassembly of claim 1 further comprising a plurality of springs locatedaround the plurality of spring pins, each spring located between eacharm and the central section.
 6. The roller assembly of claim 5 whereinthe spring pin is located in a first bore in the central section, theretaining pin is located in a second bore in the central section, thespring pin is fixed to the arm, and the retaining pin is fixed to thecentral section.
 7. The roller assembly of claim 6 wherein the roller isconstrained by the retaining pin and the spring pin to move along anaxis defined by the retaining pin.
 8. The roller assembly of claim 6wherein the spring exerts a force on each arm thereby biasing each armaway from the central section.
 9. The roller assembly of claim 5 whereinone end of the spring is located in a recess in the central section andthe other end of the spring is located in a recess in the arm.
 10. Theroller assembly of claim 1 wherein the rolling surface of the rollers isarranged to engage a polymer sheet or flexible tubing throughout a rangeof travel of the arms.
 11. A roller assembly comprising: a centralsection with a hub; a plurality of arms coupled to the central sectionsuch that each arm is capable of moving independently with respect tothe central section; a plurality of spring pins located is a pluralityof first bores in the central section, one spring pin fixed to each arm;a plurality of retaining pins located in a plurality of second bores inthe central section and fixed to the central section, one retaining pinassociated with each arm; and a plurality of rollers, one roller coupledto each arm; wherein the rollers are constrained by the retaining pinsand the spring pins to move along an axis defined by the retaining pins.12. The roller assembly of claim 11 wherein the roller is coupled to thearm via an axle and a pin.
 13. The roller assembly of claim 11 whereinthe arms and the rollers are distributed around the hub.
 14. The rollerassembly of claim 11 wherein a rolling surface of the roller isgenerally parallel to a flat surface of the central section.
 15. Theroller assembly of claim 11 further comprising a plurality of springslocated around the plurality of spring pins, each spring located betweeneach arm and the central section.
 16. The roller assembly of claim 15wherein the spring exerts a force on each arm thereby biasing each armaway from the central section.
 17. The roller assembly of claim 15wherein one end of the spring is located in a recess in the centralsection and the other end of the spring is located in a recess in thearm.
 18. The roller assembly of claim 11 wherein the rolling surface ofthe rollers is arranged to engage a polymer sheet or flexible tubingthroughout a range of travel of the arms.